An existing liquid crystal display device, such as a television, a monitor, a notebook, and the like, mainly comprises components such as a signal system, a logic board, a gate driving sub-circuit, an array substrate, a color filter substrate, etc. The gate driving sub-circuit is used for controlling a gate voltage of a thin film transistor on the array substrate to thereby control ON and OFF of the thin film transistor. The signal system is used for providing a control signal to a liquid crystal display panel. Specifically, a control signal sent by the signal system is transmitted to the logic board, and after the logic board finishes processing the control signal, a processed control signal is transmitted to the gate driving sub-circuit.
The control signal sent by the signal system typically includes a power supply signal, an image signal, a timing control signal, etc. When the image signal is abnormal or the timing control signal is abnormal, an abnormal control signal is liable to cause damage to the gate driving sub-circuit. Conventionally, when the image signal is abnormal, the liquid crystal display panel will go into a self-protection mode, in which the logic board does not receive the control signal sent by the signal system, but will generate a corresponding control signal and send it to the gate driving sub-circuit. For example, the logic board generates a full-black image signal, a certain grayscale image signal, and the like to thereby prevent the abnormal image signal from adversely affecting the gate driving sub-circuit. When the timing control signal is abnormal, the logic board of the liquid crystal display panel generally performs no processing, or performs processing in the same way as that in the case of an abnormal image signal. The above two ways of processing an abnormal control signal both enable the gate driving sub-circuit to still operate in case the control signal is abnormal. However, the gate driving sub-circuit is easily damaged if it is in an abnormal operating state for a long time, which in turn results in abnormal display in the liquid crystal display panel.